It is often desirable to add a light fixture in an existing building or structure. Adding a light in this way is called a “retrofit” operation, and may pose difficulties because wall cavities, joist cavities, attics, and the like where wiring and light fixtures are often placed may not be as accessible as they were when the building was under construction. For example, in new construction, metal cans for holding recessed lighting fixtures may be positioned between ceiling joists before any ceiling panel is installed. At that time, the joist cavity is freely accessible for fixing the can in place to the joists, attaching wiring, and the like. Once the can is in place and connected, a ceiling panel such as a drywall panel may be installed on the joists at the bottom of the joist cavity, leaving an opening at the can for inserting a bulb or trim into the can from below the finished ceiling.
However, after construction is complete, a joist cavity where lighting is desired may be completely covered by a ceiling panel, blocking access to the joist cavity. Various devices and techniques have been developed for installing retrofit lighting. For example, a round opening may be cut into the ceiling panel, for installation of a “retrofit can” having springs or other features for mounting to the ceiling panel. Once wiring is connected to the can, the can may snap into the opening to be supported by the ceiling panel. A bulb or trim can then be installed from below the ceiling.
In other cases, it may not be desirable to use a retrofit can. For example, if a low voltage light is being installed, it may be necessary to connect the light to a transformer. Line voltage wiring is connected to the transformer, which provides power at a low voltage (typically 12 or 24 volts) at its outputs. A low voltage luminaire is then attached to the output of the transformer. Preferably, the transformer is hidden within the joist cavity through an opening in the ceiling panel. The luminaire is then installed in the opening to complete a finished look.
While it may be expeditious to simply lay the transformer on top of the ceiling panel in the joist cavity, building codes may prohibit such an installation, and may require that the transformer not touch the ceiling panel.